U.S. Pat. No. 5,935,155 describes a visual prosthesis generally comprised of (1) an image acquiring and transmitting portion and (2) a receiving and retina stimulating portion. The acquiring portion includes a camera for generating a visual signal output representative of an acquired image. The stimulating portion includes an electrode array adapted to be operatively attached to the user's retina. The visual signal output is used to modulate a radio frequency (RF) carrier signal which is applied to a primary coil. A secondary coil receives the RF signal which is then demodulated to recover the visual signal output for driving the electrode array to electrically stimulate retinal tissue. In use, the acquiring and transmitting portion is mounted outside of the eye (extracellular) and the receiving and stimulating portion is primarily mounted in the eye (intraocular) The components of the intraocular portion are powered from energy extracted from the transmitted visual signal.
FIG. 1 of U.S. Pat. No. 5,935,155 comprises a functional block diagram of the visual prosthesis showing its image acquiring and transmitting portion and its receiving and retina stimulating portion. FIGS. 2 and 3 respectively show the organization of functional components of the respective portions of FIG. 1. FIGS. 4, 5, and 6 depict alternative arrangements for deploying the prosthesis physical components. In all of the figures, the primary coil is mounted in alignment with the optic axis in front of the eye, e.g., in an eyeglass lens, frame, or in a soft contact lens. In FIG. 4, the secondary coil is implanted behind the iris and a circuit housing is collocated therewith. In FIG. 5, the secondary coil is implanted behind the iris but the circuit housing is located outside of the sclera wall. In FIG. 6, the secondary coil is placed adjacent the outer sclera surface. U.S. Pat. Nos. 5,800,530 and 6,120,538 describe alternative visual prostheses.